95 Merc 40hp stops running at WOT

[Ed M]

Help, I have a 95 Merc outboard that has been running great all summer and fall. I was running wide open when I drove over a small tree branch on the river. The branch splashed water up behind the boat and and my motor sounded like it locked up. After tipping the motor up to check the prop I had water running out of two holes in front of the cover. The motor sounded like it was locked up but after a few minutes it started up. The motor idles okay and will throttle up but only idle in gear. It was dark when I got back to the pier so the following morning with hopes that it was wet electrical I tried it again. It started up and fast idles fine. It runs good slow and will accelerate fine... about 100 yards downstream it sounds like it locks up again and dies. I started it up fine and idled back to my pier. Any suggestions to start troubleshooting this problem would be appreciated. If it makes a difference I run my boat all season up north and the temps have been in the upper 20's here.

 

[hondon]

Re: 95 Merc 40hp stops running at WOT

Impact is never a good thing and with that in mind ,you should at least take a look at the condition of your gearoil.If there is impact damage, you will likley see some substantial metal flake or actual chunks of steel on the magnet of your bottom gearcase plug.If that all looks good ,there are other things to look at ,like a sheared flywheel key.

 

[Ed M]

Re: 95 Merc 40hp stops running at WOT

Thanks for your reply Hondon, I checked the lower unit oil. The oil appears to be okay there are no metal chips on the plug. I'll check the flywheel key. It wasn't really an impact but more like a entanglement...I didn't know the branch was on there until the water came splashing over the transom.

 

[masterp]

Re: 95 Merc 40hp stops running at WOT

Have you pulled the prop to see if fishing line is entangled behind it? The friction caused by running the prop could change the consistency of the fishing line. I think the key word is entanglement here!!!

 

[hondon]

Re: 95 Merc 40hp stops running at WOT

Here's another little longshot.When this thing acts up ,take the engine cover off and see if that helps.You may well have a very leaky exhaust cover.Or just run it and watch for water or smoke around the cover.That water that poured out of those two holes came from somewhere, and it is unlikely that that branch was the source.If you have an exhaust leak you will generally run fine,until you squeeze the engine.I t will then starve for air,stumble, and eventually stall.Sound familiar?